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.TH PTHREAD_MUTEX_GETPRIOCEILING 3C "Apr 1, 2008"
.SH NAME
pthread_mutex_getprioceiling, pthread_mutex_setprioceiling \- change priority
ceiling of a mutex
.SH SYNOPSIS
.LP
.nf
cc -mt [ \fIflag\fR... ] \fIfile\fR... -lpthread [ \fIlibrary\fR... ]
#include <pthread.h>

\fBint\fR \fBpthread_mutex_getprioceiling\fR(\fBconst pthread_mutex_t *restrict\fR \fImutex\fR,
     \fBint *restrict\fR \fIprioceiling\fR);
.fi

.LP
.nf
\fBint\fR \fBpthread_mutex_setprioceiling\fR(\fBpthread_mutex_t *restrict\fR \fImutex\fR,
     \fBint\fR \fIprioceiling\fR, \fBint *restrict\fR \fIold_ceiling\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBpthread_mutex_getprioceiling()\fR function returns the current priority
ceiling of the mutex.
.sp
.LP
The \fBpthread_mutex_setprioceiling()\fR function either locks the mutex if it
is unlocked, or blocks until it can successfully lock the mutex, then it
changes the mutex's priority ceiling and releases the mutex. When the change is
successful, the previous value of the priority ceiling is returned in
\fIold_ceiling\fR. The process of locking the mutex need not adhere to the
priority protect protocol.
.sp
.LP
If the \fBpthread_mutex_setprioceiling()\fR function fails, the mutex priority
ceiling is not changed.
.sp
.LP
The ceiling value should be drawn from the range of priorities for the
\fBSCHED_FIFO\fR policy. When a thread acquires such a mutex, the policy of the
thread at mutex acquisition should match that from which the ceiling value was
derived (\fBSCHED_FIFO\fR, in this case).    If a thread changes its scheduling
policy while holding a ceiling mutex, the  behavior of
\fBpthread_mutex_lock()\fR and \fBpthread_mutex_unlock()\fR on this mutex is
undefined. See \fBpthread_mutex_lock\fR(3C).
.sp
.LP
The ceiling value should not be treated as a persistent value resident in a
\fBpthread_mutex_t\fR that is valid across upgrades of Solaris. The semantics
of the actual ceiling value are determined by the existing priority range for
the \fBSCHED_FIFO\fR policy, as returned  by the \fBsched_get_priority_min()\fR
and \fBsched_get_priority_max()\fR functions (see
\fBsched_get_priority_min\fR(3C)) when called on the version of Solaris on
which the ceiling value is being utilized.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, the \fBpthread_mutex_getprioceiling()\fR and
\fBpthread_mutex_setprioceiling()\fR functions return  \fB0\fR. Otherwise, an
error number is returned to indicate the error.
.SH ERRORS
.sp
.LP
The  \fBpthread_mutex_getprioceiling()\fR and
\fBpthread_mutex_setprioceiling()\fR functions may fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value specified by \fImutex\fR does not refer to a currently existing
mutex.
.RE

.sp
.LP
The \fBpthread_mutex_setprioceiling()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The mutex was not initialized with its \fIprotocol\fR attribute having the
value of \fBPTHREAD_PRIO_PROTECT\fR.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The priority requested by \fIprioceiling\fR is out of range.
.RE

.sp
.ne 2
.na
\fB\fBEPERM\fR\fR
.ad
.RS 10n
The caller does not have the privilege to perform the operation.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	MT-Safe
_
Standard	See \fBstandards\fR(7).
.TE

.SH SEE ALSO
.sp
.LP
.BR pthread_mutex_init (3C),
.BR pthread_mutex_lock (3C),
.BR sched_get_priority_min (3C),
.BR attributes (7),
.BR standards (7)
